Radio communication by means of polarization modulation



2 Sheets-Sheet 1 G. L. USSELMAN RADIO COMMUNICATION BY MEANSOF POLARIZATION MODULATION Original Filed June, 17; 1939 Sept. 5, 1944.

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INVENTOR GEORGE L. USSELMAN ATTORNEY RADIO COMMUNICATION BY MEANS OF POLARIZATION MODULATION Sept. 5, 1944- s. L. U$S ELMAN 2 Sheets-Sheet 2 Original Filed June 17, 1939 mww Jim

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INVENTOR GEORGE L. USSELMAN H45 Patented Sept. 5, 1944 v UNITED STATES PATENT OFFICE RADIO COMMUNICATION BY MEANS OF POLARIZATION MODULATION George L. Usselman, Port Jeflerson, N. Y., assignor to Radio Corporation of America, a corporation of Delaware 7 Claims. (01. 250 6) This application, which is a division of my they may be set at any suitable angle giving best United States application Serial No. 279,656, filed results. These two antennas are connected by June 17, 1939, now Patent No. 2,273,911, granted transmission lines to the grid tank circuits 54 and February 24, 1942, concerns a new and improved 56 respectively. The tuned circuit 54 is coup ed to method and means for radio communication, the grid 58 of tube 62 while the tuned circuit 56 and, more particularly, a system of radio comis coupled to the grid 60 of tube 64. Radiomunication by means of polarization modulation. frequency amplifiers l0 and 12 may be used as It has been the practice in the prior art to shown to amplify the signals received by antransmit messages by means of amplitude, fretennas 58 and 52 for the grid circuits 54 and 56. quency or phase modulated signals, while the The anodes l4 and 1.8 of tubes 62 and 64 are present invention uses polarization modulation as connected in phase Opp t on o t e push-D a means of signalling. transformer 80. The output of transformer 88 is In describing my invention reference will be oolmeoted through audio a p fier 84 to loudm de to th att he drawings h ei Figures speaker or recorder 86. The power source for the 1 and 2 together show an embodiment of my detector is shown as 88- polarization modulation system. The principle of operation is as follows:

I Hg. 1 and Fi 2, I h a specific b i- Radio-frequency excitation voltage is supplied ment of one form of transmitter and receiver in parallel r oophasally to t e C n o grids l6 respectively for radio communication by means and [8 of tubes and 24 from the oscillator IU of polarization modulated signals, 20 Fig. 1. This carrier frequency is amplified 01' In the transmitter Fig 1 voltages char amplified and multiplied in tank vcircuits 28 and acteristic of the wave to be modulated are supand units 32 and 34 respectively, d e it plied by source m t coupling condensers H and is delivered to antennas 36 and 38 respectively. l4 and from condensers l2 and M in phase t When there is no modulation present both anthe grids Is and I8 of the two tubes 20 and 22. tonnes Will radiate energy of q l intensity but Th n des 24 and 25 of t b gland 22 are this radiated energy will be polarized in dilferent connected to the tune tank circuits 28 and 30 planes having a d po a a n angle d fernected through amplifiers or frequency multiand 33 and manner of elicitationpliers 32 and 34 respectively to antennas as and 30 NOW if audio-frequency signals a applied 33 ti l T half-wav dipole antennas from source 40, they will be delivered in phase shown in Fig. 1 are for illustration purposes and Opposition through ansfo mer T and resistors they may be any suitabl type. These antennas RI and R2 to the control grids l6 and 18 of tubes should be of a type to accentuate the polarization 0 d. 2?- This signal then modulates the radioor the radiated Waves. That is to say, the an- 35 frequency p wer to the antennas at an audio tennas 36 and 38 are of any suitable type, such rate and since the audio modulation is in phase as half-wave dipoles, which radiate waves polaropposition, the radiation of one antenna will be ized in different planes when the antennae are a maximum when that of the other te is properly excited. For example, antenna 38 may' m- T e u ant rad ated Wave energy radiate horizontally and antenna 36 may radiate 4o polarization will consequently swing back and vertically polarized waves. The antennas may forth through the radiation polarizationangle of be built in one unit or they may be built up in the antennas 36 and 38. Of'course, this newsysseparate units. tem of radio communication may also be consid- It will be noted that antennas 36 and 38 in ered as operating over two paths of thesame fre- Fig. 1 are set in quadrature or 90 fromeach quency. These two paths are oriented in space other so that the radiated waves have polarizato have different polarization. The intelligence tion angles differing by 90 though any angle or signal is transmitted by difierentiallymodumay be used that proves to be most satisfactory lating the carrier energy .of these two paths for-communication. 'which have the unlike polarization.

A source of modulating potentials 40 is coupled 0 The energy radiated from these transmitting by a transformer T to the grid-electrodes l6 and antennas travels through space and some of it I8 of tubes 20 and 22 respectively. reaches the receiving antennas shown inFig. 2.

In Fig. 2 I show a schematic circuit diagram The polarization position or direction of the of a receiver for reception of polarization modusignal energy may-change during its transmission lated ignals. and 52 are the receiving an- 55 through space but it willstill retain its polarizatennas. These .are shown was simple half-wave tion oscillation or modulation; The energy dipoles, though they may be of any suitable type picked up by receiving antennas 50 and-52, which of antenna and they may be built in one unit or are predominantly responsive to energy of a they may be separated from each other. In Fig. polarization corresponding to the polarization 2 the antennas are set at 90 from each other but of the energy radiated by antennas 36 and 3s amplified by amplifier B4 and then other antenna.

respectively, is transmitted through .amplifiers and I2 and tank circuits 54 and 56 to the grids of detector tubes 62 and 64 respectively. Tank circuits 54 and 56 are tuned to the signals received on antennas 50 and 52. The grid biases of tubes 62 and 64 should be set for maximum efficiency as detectors. Now as thepolarization of the incoming wave energy varies, it will be detected by tubes 62 and 64 and translated into low frequency or signal frequency push-pull current and voltages by transformer 80. The audiofrequency signals from transformer 80 may be the loudspeaker or recorder 86.

Antennas 50 and 52 should be of a type which is sensitive to changes in polarization of the received wave energy so that when the polarization is such that a maximum amount of energy is intercepted by one antenna, a minimum amount of wave energy is intercepted by the Then, as the polarization of the received wave energy oscillates back and forth through an angle corresponding to the rate and intensity of the audio-frequency modulating signals in the transmitter, the changes in polarization will be detected in the receiver bythe push-pull detector and amplified into audible signals in the loudspeaker.

The receiver may also be considered as a means for detecting and amplifying the signal oscillations from the transmitter which radiates carrier energy over two paths of different polarization but of the same carrier frequency, the amplitudes of the two carriers being differentially modulated according to the signal oscillations.

These specific embodiments may be modified in a number of ways. In a modification I may use a screen grid, four element tubes in the various stages of the transmitter, and, particularly, in modulator stages of the transmitter.

I claim:

l. The method of receiving wave energy the polarization of which is modulated between two limits in accordance with variations between maximum and minimum of signalling potentials which includes the steps of, intercepting wave energy the amplitude of which is maximum when the polarization of said wave energy approaches one of said lim'ts, intercepting wave energy the amplitude of which is maximum when the polarization of said radiated energy approaches the other of said limits, producing from each of said wave energies potentials varying in amplitude in accordance with the variations in amplitude of said intercepted wave energies and combining said varying amplitude potentials in an oppos ing relationship to reproduce the signal.

2. The method of receiving wave energies of like frequency and of unlike polarization and of amplitudes varying in accordance with signalling potentials which includes cepting one of said wave energies, intercepting the other of said wave energies, producing from each of said intercepted wave energies separatepotentials of varying amplitudes and so combining said varying amplitud potentials as to reproduce the signal.

3. In apparatus for demodulating wave energy the polarization of which is modulated between limits at signal frequency, a first aerial predominantly responsive to wave energy of a polarity approaching one of said limits, at second aerial the steps of, interpredominantly responsive to wave energy of a polarization approaching the other of said limits, means coupled to each of said aerials for producing a potential varying in amplitude in accordance with the approach of the polarization of the intercepted wav energy to said limits,

and means for combining said potentials in an opposing relationship to reproduce the signal.

transmitted to v and aerial adapted to radiate wave ener y 4. In apparatus for demodulating wave energies of unlike polarization the amplitudes of which are modulated between limits at signal frequency, a first aerial predominantly responsive to wave energy of one of said unlike polarizations, a second aerial predominantly responsive to wave energy of the other of said unlike polarizations, a pair of electron discharge detector tubes having input electrodes and output electrodes, means coupling the input electrodes of one of said tubes to one of said aerials, means coupling the input electrodes of th other of said tubes tothe other of said aerials, and means coupling the output electrodes of said two tubes in push-pull relation for opposing the outputs of said detector tubes.

5. In a signalling system, a first aerial adapted to radiate wave energy of a first polarization, a second aerial adapted to radiate wave energy of a second and different polarization, means for impressing wave energy of like frequency and phase on each of said aerials, means for differentially modulating said wave energies impressed on said aerials at" signal frequency whereby wave energy of a polarity which varies at signal frequency is radiated, and means for receiving and demodulating the radiated wave energy comprising a first aerial predominantly responsive to wave energy of said first polarization, a second aerial predominantly responsive to wave energy of said second polarization, a pair of electron discharge detector tubes each having input electrodes and output electrodes, means coupling the input electrodes of one of 'said tubes to one of said aerials, means coupling the input electrodes of the other of said tubes to the other of said aerials, and means coupling the output electrodes of said two tubes in push-pull relation for opposing the outputs of said detecting tubes.

6. In a signalling system, an aerial adapted to radiate wave energy of a first polarization, a secsecond and different polarization, means for impressing wave energy of like frequency and phase on each of said aerials, means for differentially modulating the amplitudes of said wave energies impressed on said aerials whereby wave energies of unlike polarization are radiated, means for receiving and demodulating the radiated wave energies, and means for opposing the outputs of said demodulating means. I

7. The method of radio signalling which comprises producing a pair of radio frequency waves polarized at different angles and simultaneously modulating in accordance with the signal the amplitude of said waves in opposite senses whereby the plane of polarization of the resultant wave is varied in accordanc with said signal, intercepting said waves, detecting the modulation on said waves and combining the detected modulations in opposing senses to reproduce the signal.

GEORGE L. USSELMAN. 

